Healthcare Worker Mortality During the 1918 Influenza Pandemic

By Amesh A. Adalja, MD, February 4, 2011

A team of researchers from the Australian Army, led by G. Dennis Shanks and funded by the U.S. Department of Defense’s Global Emerging Infections Surveillance and Response System (GEIS), recently published results of its study of mortality among nurses and physicians during the 1918 influenza pandemic.1 Lessons from that experience may be useful in current planning efforts.

Illness Common, Fatalities Relatively Rare in Armies

The team’s earlier analysis of data from the Australian Imperial Force indicated that, while rates of respiratory illness were high among nurses and physicians, deaths were rare.2 For this study, Shanks and colleagues first quantified overall mortality among nurses and physicians in the U.S. and British (England, Australia, New Zealand, and Canada) armies by reviewing military records from World War I. Deaths from nonbattle illness were attributed to influenza during peak pandemic months and were used to calculate mortality rates among military nurses and physicians.1 To determine the mortality rate among the civilian medical workforce, the researchers identified physician obituaries in national medical journals (the paper includes a graph that illustrates the dramatic peak in physician obituaries coincident with the pandemic).1

During the fall and winter months of 1918, mortality rates among physicians and nurses presumed to have influenza were 0.64% and 0.53%, respectively. The mortality rate for American nurses and physicians was higher than the rate among the British. The researchers suggest that this disparity may be due to a greater death rate in those serving domestically (ie, stateside), a finding that mirrored influenza death trends across the entire U.S. army at the time.1 It may be the case that officers on domestic duty disproportionately included new recruits who may have been exposed to virulent bacterial copathogens at a higher rate in, for example, crowded hospital wards where they were training (vs. battlefield deployed healthcare personnel).1

Explanations for Mortality Pattern

The authors posited 5 hypotheses to explain their findings of increased mortality in military personnel serving stateside. Differences in susceptibility to, or virulence of, or naturally acquired immunity to, the pandemic virus all were all considered unlikely.1 They suggest that the following 2 explanations are plausible:

Increased risk of exposure to bacterial copathogens: Following infection with influenza, certain groups may have greater likelihood of exposure to bacterial copathogens. These groups include newer recruits because they are more likely to be in an urban location, riding in troop transport ships, and exposed to crowded hospital wards.

Increased immunity to bacterial copathogens: “Seasoned” troops, urban recruits, and those who have traveled on transport ships are more likely to have had previous exposure (and therefore immunity) to bacterial copathogens.

Lessons from 1918

In 1918, there were no antibacterial and/or antiviral agents or vaccine. Little was known about the transmissibility of influenza. Infection control practices were minimal to nonexistent. And yet, of the 47,000 nurses and 46,000 physicians who delivered care in the U.S. and British armies, very few died (250 and 293, respectively).

With the protections now afforded by effective infection control practices, vaccines, therapeutics, and new technologies, along with our greatly expanded knowledge about influenza, it seems reasonable to expect that mortality among modern healthcare workers (HCW) during a pandemic would be lower than it was for nurses and doctors in 1918.

The results of this study may be somewhat reassuring for both HCW and emergency response planners, given that adequate staffing will always be essential to medical response in a pandemic. HCW must be well, willing, and able to come to work. If HCW fear for their personal safety or the safety of their families, to the extent that fear overrides a sense of duty, then staffing shortages that compromise effective response may occur. Results of studies such as this one may, to some extent, assuage fears.